The proposed study aims to develop, validate, and implement customized checklists for operating room emergencies and specialty operations in order to improve adherence to accepted safety processes and to decrease the likelihood of serious harm. The long term objective is to improve adherence to accepted processes of care by establishing checklists as standard practice in surgery, thereby improving patient safety and outcomes. Widespread adoption of checklists could reasonably be expected to significantly lower major complications and death in the more than 100 million operations performed annually in the United States. The proposed study aims to develop, validate, and implement customized checklists for operating room emergencies and specialty operations in order to improve adherence to accepted safety processes and to decrease the likelihood of serious harm. The long term objective is to improve adherence to accepted processes of care by establishing checklists as standard practice in surgery, thereby improving patient safety and outcomes. Widespread adoption of checklists could reasonably be expected to significantly lower major complications and death in the more than 100 million operations performed annually in the United States. Following the simulator study, the checklists will be implemented in three clinical sites. Sustained use of the checklists will be measured at 6 and 12 months post implementation by recording the percentage of cases in which a checklist was used for 50 cases in each of the selected specialties. Validation and evaluation of utility of the checklists will occur in real clinical scenarios via survey data of surgical teams in the selected specialties. Surveys will evaluate the perceived utility, ease of use, fit into workflow, and perceived benefit to patients, among other variables. Changes in safety attitudes at each site will be measured based on responses to the Focused Safety Attitudes Questionnaire before and after implementation of the checklists at the selected sites.